Am 24.02.2011 23:19, schrieb Edzer Pebesma:
On 02/24/2011 09:40 PM, Anna Gretschel wrote:
Dear List,
The following formula is given for a spherical model in variofit (geoR).
/rho(h) = 1 - 1.5 * (h/phi) + 0.5(h/phi)^3 if h< phi , 0 otherwise
/Could anyone explain what the term "if h<phi, 0 otherwise" means? Which
part of the equation becomes 0 if h>phi?
rho(h)
And shouldn't there be a * between 0.5 and (h/phi)?
That would have been consistent, but as this is documentatation, I don't
think it is wrong.
Thanks in advance,
Anna
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Thank you! If you don't mind I would like to ask you another question:
I want to use this function to calculate a rmse (root mean square error)
for my fitted models.
obs beeing the observed data (in my case variog$v) and pred beeing the
predicted data I use the following formula:
rmse <- function(obs, pred) sqrt(mean((obs-pred)^2))
pred I calculated like this:
pre<- 1 - 1.5 * (h/phi) + 0.5(h/phi)^3 if h< phi , 0 otherwise
with phi beeing the range and h beeing the distances (variog$u)
The output however is not reliable so I think I made a mistake but
cannot figure out what is wrong. Do you have an idea what I where the
error is in reasoning?
Thank you so much for allways replying to my beginners questions :)
Anna
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